[Mesa-dev] Immutable textures and BGRA external format support

[kalyan kondapally]

Hi,

I am looking at Immutable textures usage with image data of BGRA
format. According to Texture storage extension spec [1] if either
EXT_texture_format_BGRA8888 or APPLE_texture_format_BGRA8888 are
supported, glTexStorage2DEXT
must accept BGRA8_EXT as internal format. EXT_texture_format_BGRA8888
doesn't mention anything about BGRA8_EXT support. However,
APPLE_texture_format_BGRA8888[3] mentions supports for BGRA8_EXT as an
internal format with glTexStorage2DEXT and GL_BGRA_EXT as an external
format for TexImage2D and TexSubImage2D

glTexStorage2D is part of core in GLES3 but doesn't mention support
for BGRA8 as an internal format. Even APPLE_texture_format_BGRA8888
mentions that BGRA8_EXT is not accepted as an <internalformat>
parameter to TexImage* when the GL is OpenGL ES 3.0. With GLES3.0, I
am wondering if their is any way to use image data in BGRA format and
Immutable textures without swizzling the data to RGBA format ?

Relevant Discussion in Chromium side can be found here:
https://code.google.com/p/chromium/issues/detail?id=407034

Thanks for any pointers.

Br,
Kalyan

1)https://www.khronos.org/registry/gles/extensions/EXT/EXT_texture_storage.txt
2)https://www.khronos.org/registry/gles/extensions/EXT/EXT_texture_format_BGRA8888.txt
3)https://www.khronos.org/registry/gles/extensions/APPLE/APPLE_texture_format_BGRA8888.txt